Which example shows that the student chose a surface-level solution instead of addressing the root cause?

Correct answer: Buying only a new pen when the subject is not understood

A root-cause solution addresses the actual reason for a difficulty, whereas a surface-level solution changes something unrelated or only temporary. In option C, the problem is that the student does not understand the subject, but buying a new pen does not improve understanding, provide explanation, or create practice. Therefore, C is correct. Options A, B, and D directly respond to the identified difficulty through practice, environmental change, or clarification and note-making.